Target Details HMGB1

High-mobility group proteins were named originally since they are abundant relatively low molecular weight proteins which run quickly on SDS-PAGE gels. High-mobility group proteis box 1 (HMGB1) is one of these. The bx in the name refers to the so-called high mobility group (HMG) box, a compact domain involved in DNA binding and protein-protein interactions. The HMGB1 molecule has two of these HMG domains. The protein is also called amphoterin, this name being derived from the presence of two highly charged regions in the molecule, a relatively neutrally charged N-terminus and a very negatively charged C-terminus. In fact, the molecule is very unusually charged throughout, the human sequence consisting of 16.7% Glutamic acid, 9.3% Aspartic acid, 20% Lysine and 9.3% Arginine. HMGB1 can bind Toll like receptor 4 (TLR4) and the Receptor for Advanced Glycation End products (RAGE). TLRs are components of the innate immune system, first recognized as a family of receptors which recognize Pathogen Associated Molecular Pattern molecules (PAMPs). PAMPs are common components of bacteria and when TLRs bind these, a strong inflammatory response is activated. More recently it has been recognized that TLRs can also be activated by Damage Associated Molecular Pattern molecules (DAMPs), which are endogenous substances released from damaged and diseased cells which also bind to TLR family receptors and also activate inflammation. HMGB1 is such a DAMP, binding to TLR4, and much evidence suggests that HMGB1 is a strong activator of inflammation. Interestingly, HMGB1 is released by necrotic cells but not by apoptotic cells. The HGNC name for this protein is HBGB1.